Dual Bandpass Research Articles

Transparent dual‐band wide‐angle polarization‐insensitive single‐layer frequency selective surface for mm‐wave 5G communication systems

AbstractA highly transparent single‐layer frequency selective surface (FSS) with an optical transmittance of 92.7% at 550 nm, designed for 5G communication systems operating in dual frequency bands of 26 and 38 GHz is proposed. The dual‐band FSS not only achieves high optical transparency but also maintains good electrical performance. The transmission performance of the FSS is stable to the polarization and angles of incidence for electromagnetic waves. As a proof of concept, the FSS with periodic square loops patterned on a 188‐µm‐thick substrate is fabricated. Each loop is constructed with metallic mesh electrodes having a pitch of 10 µm. Measurements are conducted using two different systems: a free‐space measurement system and a vector network analyser‐based material characterization kit. After calibrating the measurement systems, the scattering parameters of the fabricated surface are measured. The results obtained from both measurement systems show good agreement and also agree with the simulated results. The designed surface has an insertion loss of less than 3 dB in the dual passband region. The proposed dual‐band FSS has the merits of polarization independence, angular insensitivity, and high transparency.

Design of Dual-Passband Microstrip Filtering Antenna Using Dual-Mode Closed Loop Resonators and Defected Ground Structure

This paper presents a new microstrip dual-mode closed-loop resonator (DMCLR) that is used to design lower insertion loss and better transmission dual-passband filtering antenna. The dual passband center frequencies of the presented filtering antenna are located at f_o^I=5.52 GHz and f_o^II= 6.65 GHz. The presented dual-mode, dual-passband microstrip filtering antenna results are simulated and optimized by using Computer Simulation Technology (CST) software and defected ground structure technique. Three modes of dual-mode resonators have been utilized to design the dual-passband microstrip filtering antenna and compare their results. The presented dual-mode, dual-passband microstrip filtering antenna is established on FR-4 epoxy dielectric material which has a relative permittivity ɛr= 4.3 which has height thickness h = 1.6 mm and loss tangent tan δ=0.002. Defected Ground Structure (DGS) technique has been utilized to improve the performance of the presented dual-mode, dual-passband microstrip filtering antenna.

Flexible tunable microwave photonic filter with a dual ultra-narrow passband based on a dual-wavelength Brillouin laser.

This article presents a flexibly tunable microwave photonic filter (MPF) with a dual ultra-narrow passband based on a dual-wavelength and narrow linewidth Brillouin laser. The dual passband of the filter not only exhibits ultra-high frequency selectivity but also allows for flexible and simultaneous tuning of the center frequency and interval of the passbands. In the proposed scheme, the core optical processor of the MPF consists of a dual-ring Brillouin laser resonator, which is composed of a 100-meter main fiber ring cascaded with a 10-meter secondary fiber ring. A dual-tone pump is generated through carrier-suppressed dual sideband modulation and injected into the dual-ring resonator to excite two Brillouin gains, which resonate separately in the dual-ring resonant cavity to generate a dual-wavelength single longitudinal mode Brillouin laser for processing optical RF signals. By selectively amplifying the modulated sideband signal through narrow linewidth Brillouin laser gain, the ultra-narrow dual passband are ultimately demodulated. The resulting dual filtering passband exhibits unparalleled sub-kHz bandwidth and flexible tuning capability. Experimental results demonstrate that the MPF proposed in this paper achieves an ultra-narrow dual passband of 83 Hz with a maximum side-mode suppression ratio of over 28 dB. Within the testing range of vector network analysis, the maximum tuning range of the center frequency is 20 GHz, and the passband interval can be freely tuned from 2-18 GHz. These results highlight the MPF's ability to concurrently filter dual-channel signals with high precision and its significant potential application value in ultrafine microwave frequency spectrum resolution and processing fields, such as instantaneous frequency measurement and microwave photonic sensing.

Miniaturized independent controllable dual-band bandpass filter by using transversal signal interference concepts

Abstract This paper presents and validates a compact dual-band bandpass filter with independent controllable passbands and isolation. The proposed filter is constructed by two transmission paths from input port to output port. Based on the transversal cancellation mechanism of two transmission paths, dual passband with independent controllable characteristics can be approached. The transversal cancellation techniques yield extra transmission zeros, which are located at 2.56 GHz, 3.58 GHz and 4.43 GHz respectively. Therefore, two passbands centered at 2.25/3.9 GHz are divided by triple transmission zeros. These transmission zeros also improve the out-of-band suppression performance of proposed filter. The designed prototype filter is implemented and tested, the measured 3 dB passband fractional bandwidths are 12.4 % and 7.5 %, respectively, and the minimum insertion losses are 0.48 dB and 0.88 dB respectively. Additionally, the dual-band transversal filter only occupies 0.012 λ g 2 ${\lambda }_{g}^{2}$ , which λ g is the guided wavelength at 50 Ω microstrip line at 2.25 GHz.

A miniaturized dual band pass frequency selective surface insensitive to oblique angles and polarizations of wave

Abstract A Dualband Pass Frequency Selective Structure (DPSFSS) with miniaturized elements is proposed in this article. The miniaturized elements induce high inductance and capacitance values. The meandered line concept is used which extensively increases inductance of the dipole element. Very large capacitance is obtained between two meandered elements which have wide common area perpendicular to electric field for wave propagating in Z-direction. Two pass band poles and two zeros are obtained by perpendicular arrangement of meandered patterns on two sides of the substrate. Orthogonal arrangement of patterns ensure polarization symmetry (polarization insensitive) for Transverse Electric (TE) and Transverse Magnetic (TM) modes of exciting wave. Two pass band pole frequencies are positioned at 1.84 GHz and 4.53 GHz with low Insertion Losses (IL) of 0.67 dB and 1 dB, respectively. The lower and higher frequency bands have factional bandwidths of 41 % and 46 %, respectively. The transmission nulls occupy 2.8 GHz and 6.58 GHz frequencies. The structure is miniaturized to 0.032λ 0 × 0.032λ 0 dimensions with respect to lowest resonance residing at 1.83 GHz. The low IL at both pass bands is realized despite of using a lossy FR-4 material that can be improved to less than 0.5 dB at both the bands using less lossy materials such as F4BME or RO4003C. The proposed DPSFSS design is elaborated using Equivalent Circuit Model (ECM) and Surface Current Distribution (SCD). Measurements are performed on fabricated DPSFSS prototype and it is observed that the measured results coincide well with the simulated response. Angle stability of the DPSFSS is excellent and no unwanted resonances are observed at oblique angles upto 80° for dual polarizations of wave.

A low-cost dual bandpass planar filter for WiMAX and mobile communications

This study proposes a new design of low-cost dual-bandpass filter for worldwide interoperability and microwave access (WiMAX) band at <br /> 3.50 GHz and mobile communications band at 1.19 GHz. A high pass filter and a stopband filter make up the new dual-bandpass filter structure. Different theoretical studies were carried out for the design of the proposed filter. This filter’s base is a RO5880 substrate with a dielectric permittivity constant of 2.2, loss tangent of 0.0009 and 1.6 mm thickness. High mashing density was used to validate the various simulated structures while accounting for two numerical methods: the moment technique and the finite integration method. The final circuit's overall dimensions are 60×178,3 mm<sup>2</sup>.

Design of Miniaturized Dual Band-Pass Filter for ISM and Sub-6 GHz Spectrum by Employing Square Complementary Split Ring Resonator

Design of Miniaturized Dual Band-Pass Filter for ISM and Sub-6 GHz Spectrum by Employing Square Complementary Split Ring Resonator

Двошаровий Т-подібний навантажений шпильковий резонатор для двоcмугового смугопропускного фільтра з покращеними параметрами

В статті розроблено простий високоефективний компактний двосмуговий фільтр на основі багатошарового Т-подібного навантаженого шпилькового резонатора T-SLHR (T-shape loaded hairpin resonator). В схемі розробленого фільтра використано дві підкладки. На заземленій площині першої підкладки реалізовані два резонатори T-SLHR, які електрично зв’язані через просторовий зазор S, завдяки чому досягається необхідна подвійна смуга пропускання. На другій незаземленій підкладці розташовується заземлений шпильковий шлейф, вхід/вихід якого з’єднується з T-SLHR для отримання необхідної характеристики фільтра. Для перевірки запропонованої концепції реалізовано двосмуговий смуго-пропускний фільтр BPF (bandpass filter) для системи багатоканальної бездротової мережі, що працює на центральних частотах 2,4 ГГц і 3,5 ГГц. Крім того, на основі теорії непарних і парних мод аналізується можливість генерації заданих частот за допомогою T-SLHR. Також, представлена блок-схема за допомогою якої пояснюється механізм зв’язку та очікувані характеристики фільтра. Крім того, змодельований фільтр був виготовлений, і отримані результати вимірювань і моделювання порівняні та проаналізовані. Виготовлений фільтр має досить малу площу менше 126 мм2, високу вибірковість завдяки високій крутизні скатів характеристики фільтра та високий рівень смуг загородження.

Miniaturized metallic symmetrical resonator backed CPW inspired dual band filter using Meander line for 5G mm‐wave applications

AbstractAn ultra‐miniaturized symmetrical resonator backed coplanar waveguide based dual band pass filter using Meander line for 5G mm‐wave applications is presented. Meander line CPW structure with ultra miniaturized size was designed, investigated and its equivalent circuit was extracted using theoretical and experimental results to explore basic RF characteristics. The resonator at the back side of the substrate is symmetrical in both horizontal and vertical plane. This resonator is electrically coupled with the Meander line structure in the conducting plane. Symmetrical resonator structure coupled with open stubs on both sides on ground plane and Meander line structure with uniform spacing implemented at the conducting layer constitutes the metallic backed Co‐Planar waveguide based dual band filter. By using Meander line, the overall size of the communication devices has been reduced in large scale. The combination of symmetrical resonator and Meander line structure produces the overall bandwidth from (1 to 30) GHz. 5G mm‐wave filter operates in two bands; Band I operates from (1 to 14.2) GHz with insertion loss −1.8 dB and return loss −34 dB with fractional bandwidth of 73.6%; Band II operates from (16.2 to 30) GHz with insertion loss −1.2 dB, return loss −30 dB and fractional bandwidth of 59.7%. The overall filter circuit geometry is (5 × 5 × 1.6) mm and in terms of wavelength: (0.52 × 0.52) λg.

Dual-Band and Wideband Bandpass Filters Using Coupled Lines and Tri-Stepped Impedance Stubs.

In this paper, two bandpass filters-one with a dual-band response and the other with a wideband response-were designed, implemented, and experimented with. The filters are based on the novel combination of series coupled lines and tri-stepped impedance stubs. However, coupled lines along with tri-stepped impedance open stubs (TSIOSs) give a third-order dual passband response. The advantage of dual-band filters using coupled lines and TSIOSs is that they have wide passbands that are close together and separated by a single transmission zero. In contrast, the inclusion of tri-stepped impedance short-circuited stubs (TSISSs) instead of TSIOSs provides a fifth-order wide passband response. The advantage of wideband bandpass filters using coupled lines and TSISSs is that they have a very good selectivity factor. Theoretical analysis was carried out to validate both filter configurations. The tested bandpass filter using coupled lines and TSIOS units had two close wide passbands operating at 0.92 and 1.52 GHz center frequencies, respectively. The dual-band bandpass filter was implemented to operate in GSM and GPS applications. The first passband had a 3 dB fractional bandwidth (FBW) of 38.04%, while the second passband had a 3 dB FBW of 22.36%. The experimental result of the wideband bandpass filter (with coupled lines and TSISS units) had a center frequency of 1.51 GHz with a 3 dB fractional bandwidth of 62.91% and a selectivity factor of 0.90. A good congruence was demonstrated between the full-wave simulated and tested results for both filters.

Design and characteristic analysis of uniplanar multiband frequency selective surface for GSM, LTE, WLAN, ISM, WiMAX and X‐band applications

AbstractThe uniplanar compact, affordable, and unique slot‐based multiband frequency selective surface (FSS) of periodic cell size 0.14λc × 0.14λc (λc is wavelength at the initial stopband resonance) is presented in this article. The quadband FSS is analyzed using full‐wave simulation, circuit simulation (ECM), and experimental measurement where good agreement is attained. The FSS offers polarization independence with steady responses for all angular variations in the TE plane and up to 45° in the TM plane. The FSS offers dual stopbands at 2.75–4.15 and 9.45–12.48 GHz and dual passbands at 0.001–0.8 and 4.74–5.6 GHz that includes spectrum coverage of GSM, LTE, WLAN, ISM, WiMAX, and most part of X‐band communication.

Design of dual-mode resonators based on laterally coupled alternating thickness (LCAT) modes for WiFi 2.4G and n77 dual-passband filter

This paper explores a dual-mode resonator that uses laterally coupled alternating thickness (LCAT) modes, and a dual-passband filter for WiFi 2.4G and n77 bands is constructed. The resonator's frequency can be adjusted by the electrode thickness, period and piezoelectric film thickness, and their effects on the quality factor (Q) values and effective electromechanical coupling coefficient (k2eff) were analyzed. In addition, the impact of Sc-doped concentration on resonators' performance was investigated, and the AlSc0.35N-based resonators exhibited both high Q and k2eff values. Furthermore, two resonant modes were effectively excited by setting two working regions. Adding an acoustic blocking groove reduces mutual acoustic energy leakage, increasing Q values for target modes and suppressing spurious signals. The dual-mode resonator’ structure were further optimized to ensure that both modes have similar high performance. Ultimately, this work constructs a dual passband filter with center frequencies of 2.49 and 3.54 GHz with 75 and 132 MHz bandwidths respectively, and achieves over 60 dB out-of-band rejection.

Design of a dual-band filter with high selectivity and wide stopband

ABSTRACT This paper proposes a design of dual-band bandpass filter with a high selectivity and a wide stopband, by using two ring type hairpin resonators. The equivalent circuit of the used resonator is analyzed through the analysis of odd and even modes. The designed filter can achieve dual passbands at 2.4 GHz and 3.65 GHz for wireless local area network (WLAN) and 5 G communication systems, with transmission zeros at 2.9 GHz and 5.1 GHz, realizing high selectivity. With a wideband bandstop filter on the input port, a wide stopband from 4.6 GHz to 17.3 GHz is realized.

Design of a Dual Band-pass Filter Using Fork-type Open Stubs and SIR Structure

Design of a Dual Band-pass Filter Using Fork-type Open Stubs and SIR Structure

Dual-band filter design based on hourglass-shaped spoof surface plasmon polaritons and interdigital capacitor structure

In this paper, a dual passband filter with spoof surface plasmon polaritons (SSPPs) and interdigital capacitance structure loaded on a coplanar waveguide (CPW) is proposed. First, the hourglass-shaped SSPP unit-cell structure and the interdigital capacitor structure are introduced on the coplanar waveguide transmission line to obtain high fractional bandwidth and low insertion loss passband characteristics. Then, a dual passband filter is formed by loading the interdigital capacitor loop resonator to excite the trapped waves. The simulation results show that the proposed dual passband filter has excellent upper sideband rejection and dual passband filtering performance. The fractional bandwidths of the two passbands of the design are 46.8% (1.49–2.40 GHz) and 15.1% (2.98–3.63 GHz), respectively, which can achieve more than –40 dB rejection in a range of 4.77–7.48 GHz. The upper cutoff frequency and lower cutoff frequency of the two passbands can be independently regulated by changing the structural parameters of the proposed filter. In order to gain a more in-depth understanding of the operating principle of the dual passband filter, the corresponding dispersion curves and electric field distribution, LC equivalent circuit analysis are given. Finally, the prototype of the designed filter is fabricated according to the optimized parameter values. The experimental results are in good agreement with the simulation ones, indicating that the proposed dual-passband filter is of great importance in implementing microwave integrated circuits .

Investigations on Complementary Split Ring Resonator (CSRR) array integrated printed conformal band pass filters for modern wireless communication applications

This paper presents the performance analysis of two different conformal band pass filters (BPFs) loaded with an array of circular complementary split ring resonators (CSRRs). Type-1 bandpass filter has been designed by integrating a 9 × 9 array of circular complementary split ring resonator on the bottom layer of the filter. Similarly, Type-2 bandpass filter has been constructed by loading an array of 5 × 5 split ring resonator on the patch layer of the filter. A comparative study between Type-1 and Type-2 bandpass filters are also evaluated that shows dual pass bands for Type-1 filter and triple pass bands for the Type-2 bandpass filter. Furthermore, the conformality of both bandpass filters are judged through bending deformation analysis with various bending positions at 15°, 30°, 45°, 60° and 90°. During the bending performance analysis, the suggested BPFs retains the dual and triple pass band characteristics without any major deviations in its characteristic's parameters. Various performance parameters like return loss, insertion loss, group delay, bandwidth, and quality factor are measured. Detailed analysis of E and H field distributions and surface current distributions are also presented. The Type-2 bandpass filter shows better performance in terms of filter properties compared to Type-1 band pass filter. Hence, the prototype of Type-2 filter with an area of 30 × 30 mm2 is fabricated and measured. The validated results are agreed with the simulated results which confirms the applicability of the proposed filter for several modern wireless communication applications such as Wi-Max and personal communication systems (PCS) applications.

A dual‐band reconfigurable filtering antenna using PIN diodes for WiMAX and WLAN applications

The realization of a compact dual band reconfigurable filtering antenna is described for WiMAX and WLAN application through this communication. First and foremost, a dual band filter is offered employing four open ended half wavelength Stepped Impedance Resonators (SIRs) to resonate at 3.2 GHz and 5.35 GHz. PIN diodes have been connected to the edges of the innermost resonators to switch the operation from dual passband to two different single passbands and to all stop configuration. Multipath coupling helps to create transmission zeroes on either side of passband enriching the selectivity. In order to implement the filtering antenna, a compact monopole antenna is presented using two triangular radiating patches radiating at 3.2 GHz and 5.35 GHz. Finally, the filter and the antenna structures are combined to accomplish the proposed dual band reconfigurable filtering antenna. The results with reference to return loss and radiation pattern are provided and good performances are obtained. The suggested filtering antenna has the reflection coefficient lower than −16 dB for all the desired operating bands. As well, it offers gain of about 3.21 dBi and 5.08 dBi at the two radiating bands. The developed prototype is fabricated and measured to examine the anticipated and simulated results where a close agreement is established between them.

Compact Dual Bandpass Filter Using Dual-Split Ring Resonator for 5G Upper Microwave Flexible Use Services

A novel, compact dual bandpass filter design is proposed for 5G upper microwave flexible use services. To realize the proposed design, a dual split-ring resonator structure coupled to the microstrip transmission line is used. The output responses have been validated using vector network analyzer N5222A. The measured filter records a frequency range of 23.8 GHz–25.98 GHz for the first passband and 28.05 GHz–28.7 GHz for the second band, with fractional bandwidths of 8.8% and 2.2%, respectively. The minimum insertion loss is observed to be 4.2 dB using microstrip technology, even at higher frequencies. The proposed design occupies the area of 0.4 λg×0.27 λg, where λg is guided wavelength at the lower band central frequency. Simulated and measured results are approximately compatible with each other. The proposed design is useful for fixed satellite service earth stations, terrestrial wireless operations, and 5G mobile communications applications.

Dual Pass Band Filter using Quad Stub Loaded Uniform Impedance Resonator

A low loss, highly selective and miniaturized dual pass band filter for the wireless (WiMAX, WLAN) application is proposed in this paper. The filter is designed with Multimode resonators, constructed with Uniform Impedance Resonator (UIR) and multiple open stubs. Two different coupling schemes (electronic and magnetic) are observed for the said dual pass bands. A detail analysis about the dimension of the resonators, resonating conditions and frequency calculations are presented in this paper. The dual pass bands are achieved at 3.45 GHz and 5.4 GHz with minimum pass band insertion loss (|IL|) 0.1 and 0.18 dB and the pass band Fractional Band widths (FBW) 4% and 8% respectively. With proper optimizations, Transmission Zeros (TZ) are achieved on both sides of the dual pass bands and the spurious pass band are kept around -20dB level and hence good selectivity is achieved. The overall size of the filter is optimized for the best possible results in terms of Insertion Loss, Return Loss and selectivity, is found to be (24.2 x 21)mm = (0.28 x 0.24)λg = 0.06 λg2.

Balanced quasi-elliptic-type dual-passband filters using planar transversal coupled-line sections and their digital modeling

AbstractA class of balanced dual-band bandpass filters (BPFs) with planar transversal-signal-interference coupled-line sections is reported. In their building balanced dual-band BPF stage under differential-mode excitation, a second-order quasi-elliptic-type dual-band bandpass filtering transfer function is obtained. Specifically, from the transversal interaction among their two open-ended and virtually-short-ended half-wavelength coupled-line paths, sharp-rejection differential-mode dual passbands with several out-of-band transmission zeros at both sides are realized. To attain high common-mode suppression levels within the differential-mode passbands, two open-ended line segments are connected at the symmetry plane of the devised balanced dual-band BPF stage. Moreover, higher-order schemes based on in-series-cascaded multi-stage designs to further increase differential-mode selectivity and in-band common-mode rejection are illustrated. The operational principles and parametric-analysis design rules of the engineered transversal-coupled-line-based balanced dual-band BPF approach are detailed. Additionally, for a rigorous interpretation of their zero/pole characteristics, a digital-modeling framework is applied to them to connect RF balanced filters with their discrete-time versions. For practical-validation purposes, a microstrip prototype of two-stage/fourth-order balanced dual-band BPF is built and tested. It exhibits measured differential-mode dual passbands with center frequencies of 1.464 GHz and 2.294 GHz, 3-dB fractional bandwidths of 8.74% and 9.68%, and in-band common-mode rejection levels above 23.16 dB and 31.36 dB, respectively.